Trailing comma in `$COPILOT_AGENT_FIREWALL_ALLOW_LIST` causes error

[jonathanpeppers]

Describe the bug

On accident, I left a trailing comma in $COPILOT_AGENT_FIREWALL_ALLOW_LIST such as:

microsoft.com,visualstudio.com,

And then the next Copilot request errored on the Processing Request step:

----
panic: Invalid rules provided

goroutine 1 [running]:
github.com/github/ebpf-padawan-egress-firewall/pkg/rules.SplitDomainUrlOrIPListByType(0x1, {0xc000037b08, 0x27, 0x10?})
	/home/runner/work/ebpf-padawan-egress-firewall/ebpf-padawan-egress-firewall/pkg/rules/legacy_firewall_items.go:109 +0xca6
github.com/github/ebpf-padawan-egress-firewall/pkg/rules.BuildRules({0xc000037b08, 0x27, 0x47}, {0x0, 0x0, 0x0}, {0x0, 0x0, 0x400000008?}, {0x0, ...})
	/home/runner/work/ebpf-padawan-egress-firewall/ebpf-padawan-egress-firewall/pkg/rules/rules.go:116 +0x315
main.main()
	/home/runner/work/ebpf-padawan-egress-firewall/ebpf-padawan-egress-firewall/cmd/main.go:154 +0xda5
Error: Process completed with exit code 2.

Removing the trailing , fixed this.

Expected behavior

It seems like a trailing , should be OK and everything still work.

Additional context

Example here: https://github.com/dotnet/android/actions/runs/15640310139/job/44065837045#step:9:69

[nhu-do]

Hi @jonathanpeppers this is working as expected, as a trailing comma breaks the syntax. One thing that might be nice here though is validation of the list syntax prior to execution, similar to how we validate MCP configuration prior to saving. I'll add that as an enhancement for our team.

[jonathanpeppers]

@nhu-do I just know if I did string.Split() in C#, there is an option to ignore empty entries which would "just work".

The UI I used was for general environment variables:

Which, doesn't seem like a great place to validate this, as you can put any value in here.

[nhu-do]

@jonathanpeppers Based on your feedback, we've improved the configuration experience to be more user friendly and validate changes prior to running the agent, whether you enter addresses via Actions variables or the new UI. Check out the changelog here, and would love to hear your feedback as to whether this improves the root problem. 🙏🏼

[jonathanpeppers]

The new settings screen seems like it solves this issue, thanks!

• https://github.blog/changelog/2025-07-15-configure-internet-access-for-copilot-coding-agent/

I'll probably just delete the env var I had before and see if the recommended rules work for us.